Alloy



Patented Nov. 5, 1935 James M. Lohr, Morristown, N. 3., ass'ignor to Driver-Harris Company, Harrison, N. 1, a corporation of New Jersey No Drawing. Application .ie it. less, Serial No. 26,619

2 Glalms.

/ tion are characterized by the ability to resist oxidation and by a prolonged life, exceeding-that of other known alloys, when used under high temperature conditions.

While nickel-chromium'and nickel-chromiumiron alloys having the abiilty to resist oxidation at high temperatures are known, their period of usefulness in service is often not as long as desired. I have found that the addition ofsmall quantities of calcium and zirconium to such nickel-chromum alloys greatly increases their period of life when employed under conditions where they are subjected to high temperatures. The alloys forming the subject matter of the present application may also contain small quantitles of either silicon or manganese or both of these elements. a

In carrying out my invention'I add small quantitles of calcium and zirconium, with or without silicon or manganese to nickel-chromium or nickel-chromium-iron alloys. The nickel-chro- 'mium alloy most generally used in the art consists of 80 parts of nickel and 20 parts of chromium and I find it advantageous to add the other metals mentioned above to nickel-chromium alloys of substantially these proportions. The proportions of nickel and chromium in the alloy may be varied. Thus the chromium content may be from 15 to 25 percent and the balance nickel.

Likewise the most generally used proportions of nickel, chromium and iron in'nickel-chromiumiron alloys is 60 percent nickel, 10 to 15 percent chromium and the balance iron and I find it advantageous to employ substantially these proportions of those ingredients, adding the calcium and zirconium. These proportions may also be varied, the nickel, however, forming the major part of the alloy, and the nickel-chromium con tent being such that the alloy will have the characteristics of a non-ferrous alloy.

In preparing alloys containing the additional elements enumerated, the quantities of the additional elements are subtracted from the nickel content, as for example, when calcium and zicronium are added to an alloy containing 15 to 25 percent chromium and the balance nickel, the final alloy will contain 15 to 25 percent chromium, calcium and zirconium in the percentages herein stated and the balance nickel.

The proportions of calcium and zirconium may vary within certain limits. I have found that best results are obtained when these metals are present in the nickel-chromium or nickel-chromium-iron alloy within the following limits: p

' Percent Calcium .01- .20

Zirconium .Ol- .50

If manganese or silicon are employed, they may in be used within the following limits:

Percent Nickel-chromium and nickel-chromium-iron alloys containing the above ingredients within the proportions given have been found by tests 25 to have a'greatly increased period of life when exposed to high temperatures. For the purpose of determining the life of such alloys at high temperatures I have tested them by the method of test outlined in Tentative Accelerated Life Test for Metallic Materials for Electrical Heating oi the American Society for Testing Materials, described in vol. 29 of the "Proceedings of the Thirty-second Annual Meeting of the American Society for- Testing Materials beginning on page 613. The method is substantially as follows:

A sample of the wire to be tested, free from kinks, approximately twelve inches long and of about .025" diameter, is mounted vertically on the test board, the upper end being held in position by means of a suitable binding post. A 10 gram weight is attached to the lower end of the specimen. A short piece of wire is attached to the 10 gram weight and projects downward into a cup of mercury where it may move freely up and down. A rheostat' and an interrupter are connected in series with the specimen tothe power supply. The test is run on constant temperature at a standard temperature chosen for the alloy under consideration for the first twenty-- four hours. Thereafter it is run on constant voltage to the burnout. The life in hours up to a 10 percent increase in resistance is known as useful life while the life to the burnout is known as total life. Throughout the test the power is M on two minutes and oil two minutes. This is accomplished by means of an interrupter.

In testing the alloys of my invention according to the above described method a reference sample composed of 80 percent nickel and 20 per- Per 1: useful 1m 01 12 494 03 21 515 0a .20 45a 05 24 425 0c .20 455 It will be noted that the useful life of such samples is from 425 percent to 515 percent of the standard sample. Theuse of calcium and zirconium, therefore, greatly increases the useful life of the alloy for electrical resistance purposes where the wire is exposed to high temperatures.

In the alloys referred to herein small amounts of phosphorous and sulphur may be present as impurities. The nickel may also contain about .1 percent of cobalt.

I claim:

1. A nickel-chromium alloy containing 15 to 25 percent chromium, .01 to .20 percent calcium, .01 to .50 percent zirconium, balance nickel.

2. A nickel-chromium alloy containing 15 to 15 

